This application is based on Japanese Patent Application No. 2002-175109, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates to improvements in a planetary gear device provided in a power transmitting system of an automotive vehicle, for transmitting a drive force produced by a drive power source.
2. Discussion of Related Art
A power transmitting system of an automotive vehicle may incorporate a planetary gear device including (a) a sun gear disposed rotatably about an axis thereof, which is an axis of the planetary gear device, (b) a ring gear disposed rotatably about an axis thereof concentric with the axis of the planetary gear device, (c) a carrier having a pinion pin parallel to the axis of the, planetary gear device and disposed rotatably about an axis thereof concentric with the axis of the planetary gear device, the pinion pin rotatably supporting a pinion such that the pinion is held in meshing engagement with the sun and ring gears, and (d) a clutch for connecting a selected one of the sun gear, ring gear and carrier to another rotary element. JP-A-2001-108076 discloses an example of the planetary gear device of the type described above. The planetary gear device functions to switch a direction of transmission of the drive power source between forward and reverse directions, and/or change the speed ratio of the power transmitting system.
Where the planetary gear device of the type described above is arranged such that the ring gear is connected through the clutch to another rotary element, for example, there are coaxially disposed: (i) a clutch drum having a plurality of engaging grooves formed in its inner circumferential surface and parallel to the axis of the planetary gear device; (ii) a plurality of friction members in the form of clutch plates fitted in the clutch drum such that the clutch plates are rotatable with the clutch drum and axially movable relative to the clutch drum, each of the clutch discs having a plurality of engaging teeth formed on its outer circumferential surface and held in engagement with the respective engaging grooves of the clutch drum; (iii) an abutting member in the form of a backing plate having a plurality of engaging teeth formed on its outer circumferential surface, fixed in the clutch drum at the engaging teeth thereof and disposed on one side of a series of the clutch plates such that the backing plate is rotatable with the clutch drum and abuttable on the nearest clutch plate; (iv) the above-indicated ring gear disposed adjacent to the backing plate, and having a plurality of engaging teeth formed on its outer circumferential surface and held in engagement with the engaging groove of the clutch drum; and (v) a piston slidably fitted in the clutch drum and disposed on the other side of the series of clutch plates such that the piston is axially movable relative to the clutch drum, to press the clutch place toward the backing plate. The above-indicated rotary element connected through the clutch to the ring gear is integrally fixed to an attaching member which is disposed coaxially with the clutch drum and which has a plurality of engaging grooves formed on its outer circumferential surface and parallel to the axis of the planetary gear device. A plurality of clutch discs in the form of annular members are fitted on the attaching member such that the clutch discs are rotatable with the attaching member and are axially movable relative to the attaching member, each of the clutch disc having a plurality of engaging teeth formed on its inner circumferential surface and held in engagement with the engaging grooves of the attaching member. The clutch plates and the clutch discs are arranged alternately in the axial direction. In this planetary gear device, the clutch drum and the piston cooperate to define a fluid chamber. When a pressurized fluid is delivered into the fluid chamber, the piston is axially moved to force the clutch plates and the clutch discs against each other and against the backing plate, so that the ring gear is mechanically connected to the above-indicated rotary element through the clutch plates and clutch discs which are held in pressing frictional contact with each other.
The clutch drum has three annular grooves formed in its inner circumferential surface in its circumferential direction, and three retainer rings (annular stop members) are fitted in the respective annular grooves such that the two retainer rings are disposed on the respective opposite sides of the ring gear while the third retainer ring is disposed on one side of the backing plate remote from the piston, and such that the retainer rings are almost radially aligned with the engaging teeth of the ring gear and the backing plate, which are disposed in the clutch drum such that the ring gear and backing plate are rotatable with the clutch drum. The retainer rings function to prevent the ring gear and backing plate from being axially moved relative to the clutch drum in the axial direction.
The present inventors have continued an extensive research for a long time in an effort to provide a planetary gear device for a vehicle, which is economical to manufacture. As a result of this research, the inventors have conceived an arrangement which permits reduction in the number of required components associated with the clutch which is provided to connect the ring gear and another rotary element to each other. The present invention was made in the light of the background art described above. It is an object of the present invention to provide a planetary gear device for a vehicle, which is simple in construction and economical to manufacture.
The object indicated above may be achieved according to any one of the following modes of the present invention in the form of a planetary gear device for an automotive vehicle, each of which is numbered like the appended claims and depends from the other mode or modes, where appropriate, for easier understanding of technical features disclosed in the present application, and possible combinations of those features. However, it is to be understood that the invention is not limited to those technical features or combinations thereof.
(1) A planetary gear device for an automotive vehicle, comprising (a) three rotary elements consisting of a sun gear, a carrier and a ring gear, (b) a clutch drum having a plurality of engaging grooves formed in its inner circumferential surface and parallel to its axial direction, (c) a plurality of friction members fitted in the clutch drum such that the friction members are rotatable with the clutch drum and axially movable relative to the clutch drum, each of the friction members having a plurality of engaging teeth formed on its outer circumferential surface and held in engagement with the respective engaging grooves of the clutch drum, (d) an abutting member having a plurality of engaging teeth formed on its outer circumferential surface, fixed in the clutch drum at the engaging teeth thereof and disposed on one side of a series of the friction members such that the abutting member is rotatable with the clutch drum and abuttable on a nearest one of the friction members, and (e) a piston slidably fitted in the clutch drum and disposed on the other side of the series of the friction members such that the piston is axially movable relative to the clutch drum, to press the friction members toward the abutting member, and wherein the ring gear has a plurality of engaging teeth formed on its outer circumferential surface, fixedly fitted in the clutch drum at the engaging teeth thereof such that the ring gear is rotatable with the clutch drum, the planetary gear device further comprising:
a first retainer ring and a second retainer ring which are fixed on the clutch drum, to prevent axial movements of the abutting member and the ring gear relative to the clutch drum, the first retainer ring being disposed between and in contact with the engaging teeth of the abutting member and the engaging teeth of the ring gear, while the second retainer ring being disposed on one side of a radially outer portion of the ring gear having its engaging teeth, which one side is remote from the piston, the second retainer ring being held in contact with the engaging teeth of the ring gear.
In the planetary gear device constructed according to the above mode (1) of the invention wherein the abutting member and the ring gear are disposed in the clutch drum, the axial movements of the abutting member and the ring gear relative to the clutch drum can be effectively prevented by the first and second retainer rings fixed on the clutch drum. The first retainer ring is disposed between the abutting member and the ring gear, in contact with the engaging teeth of the abutting member and the engaging teeth of the ring gear, while the second retainer ring is disposed on one side of the radially outer portion of the ring gear which has the engaging teeth, which one side is remote from the piston. The second retainer ring is held in contact with the engaging teeth of the ring gear. Thus, the abutting member and the ring gear are fixed on the clutch drum by only two retainer rings, that is, by the first and second retainer rings, such that the abutting member and the ring gear are not axially movable relative to the clutch drum. Accordingly, the present planetary gear device is simpler in construction and more economical to manufacture, with a smaller number of the required components, than the known planetary gear device which requires at least three retainer rings.
(2) A planetary gear device according to the above mode (1), wherein the first and second retainer ring are fixed on the inner circumferential surface of the clutch drum in which the plurality of engaging grooves are formed.
(3) A planetary gear device according to the above mode (1) or (2), wherein the above-indicated radially outer portion of the ring gear is an outwardly extending flange formed at one axial end of the ring gear which is adjacent to the abutting member.
(4) A planetary gear device for an automotive vehicle, comprising (a) three rotary elements consisting of a sun gear, a carrier and a ring gear, (b) a clutch drum having a plurality of engaging grooves formed in its inner circumferential surface and parallel to its axial direction, (c) a plurality of friction members fitted in the clutch drum such that the friction members are rotatable with the clutch drum and axially movable relative to the clutch drum, each of the friction members having a plurality of engaging teeth formed on its outer circumferential surface and held in engagement with the respective engaging grooves of the clutch drum, (d) an abutting member having a plurality of engaging teeth formed on its outer circumferential surface, fixed in the clutch drum at the engaging teeth thereof and disposed on one side of a series of the friction members such that the abutting member is rotatable with the clutch drum and abuttable on a nearest one of the friction members, and (e) a piston slidably fitted in the clutch drum and disposed on the other side of the series of the friction members such that the piston is axially movable relative to the clutch drum, to press the friction members toward the abutting member, and wherein the ring gear has a plurality of engaging teeth formed on its outer circumferential surface, fixedly fitted in the clutch drum at the engaging teeth thereof such that the ring gear is rotatable with the clutch drum, the planetary gear device being characterized in that:
the abutting member and the ring gear are formed integrally with each other, as a one-piece member; and
at least one retainer ring is fixed on the clutch drum to prevent axial movements of the one-piece member relative to the clutch drum, the at least one retainer ring being disposed in contact with the engaging teeth of the abutting member and the ring gear.
In the planetary gear device constructed according to the above mode (4) of this invention, the abutting member and the ring gear disposed in the clutch drum are formed integrally with each other, as a one-piece member, and the axial movements of this one-piece member relative to the clutch drum can be effectively prevented by the at least one retainer ring which is disposed in contact with the engaging teeth of the abutting member and the ring gear. Thus, the abutting member and the ring gear that are formed as the one-piece member are fixed on the clutch drum by one retainer ring or two retainer rings, such that the abutting member and the ring gear are not axially movable relative to the clutch drum. Accordingly, the present planetary gear device is simpler in construction and more economical to manufacture, with a smaller number of the required components, than the known planetary gear device which requires at least three retainer rings.
(5) A planetary gear device according to the above mode (4), wherein the above-indicated at least one retainer ring is fixed on the inner circumferential surface of the clutch drum in which the plurality of engaging grooves are formed.
(6) A planetary gear device according to the above-indicated mode (4) or (5), wherein the ring gear has an outwardly extending flange formed at one axial end thereof on the side of the clutch drum, and the abutting member is formed integrally with the outwardly extending flange such that the abutting member is spaced apart from the outwardly extending flange in an axial direction of the clutch drum. In this case, the at least one retainer ring consists of a single retainer ring interposed between the outwardly extending flange and the abutting member.
(7) A planetary gear device according to the above mode (4), wherein the one-piece member has a plurality of common engaging teeth which function as the engaging teeth of the abutting member and the engaging teeth of the ring gear, and the above-indicated at least one retainer ring includes a retainer ring which is disposed on one side of a radially outer portion of the one-piece member which has the common engaging teeth. The above-indicated one side is remote from the piston.
(8) A planetary gear device according to the above mode (7), wherein the clutch drum includes a first axial portion having an inner circumferential surface in which the engaging grooves are formed as first engaging grooves, and a second axial portion having an inner circumferential surface in which a plurality of second engaging grooves are formed, and the common engaging teeth are held in engagement with the second engaging grooves.
(9) A planetary gear device according to the above mode (8), wherein the second axial portion has a larger diameter than the first axial portion and is located on one side of the first axial portion which is remote from the piston, and the first and second axial portions cooperate with each other to define a shoulder surface. In this case, the above-indicated one retainer ring consists of a single retainer ring disposed on the above-indicated one side of the radially outer portion of the one-piece member, and the common engaging teeth are held in abutting contact with the shoulder surface.
(10) A planetary gear device according to the above mode (8), wherein the first and second axial portions have a same diameter, and the second axial portion is located on one side of the first axial portion which is remote from the piston. In this case, the one-piece member has a plurality of second engaging teeth formed such that the common engaging teeth and the second engaging teeth are arranged alternately in a circumferential direction of the one-piece member, and the second axial portion has a plurality of cutouts formed such that the second engaging teeth are held in engagement with the respective cutouts. Further, the first axial portion has axial end faces which are exposed to the respective cutouts and which provide abutting faces. In this case, the above-indicated least one retainer ring consists of a single retainer ring disposed on the above-indicated one side of the radially outer portion of the one-piece member, and the second engaging teeth are held in abutting contact with the abutting faces of the first axial portion of the clutch drum.
(11) A platen device according to the above mode (7), wherein the above-indicated at least one retainer ring consists of the retainer ring disposed on the above-indicated one side of the radially outer portion of the one-piece member, and an auxiliary stop member fixedly disposed on the other side of the radially outer portion of the one-piece member.